Piston expander



March 21, 1939. G. c. BECK 2,151,071

PISTON EXPANDER Filecj Dec. 22, 1937 INVENTOR eory C'Zeck Patented Mar. "21, 1939.

UNITED STATESv PATENT OFFICE .z,151,ou I

rIs'roN EXPANDER George 0. Beck, Spokane, Wash. I Application December 2'2, 1931, Serial No. 181,057

2 Claims. (01. 309-12) It is a feature of this invention to provide an,

5 expander means that is self-sustaining in the performance of its function.

' It is a further feature to provide an expander means that is secured to the skirt, either 'when initially manufactured or later as' an accessory,

10 and which is adapted to perform its expanding function without being detached from the skirt.

A further feature consists in a self-sustaining expander that performs its function by having its shape altered.

A further feature consists in an expander that is self-sustaining but which is also capable of yielding under the recoil of excessive expansion of the skirt.

The invention resides and is claimed in com- 20 bination with a piston and also as an article of manufacture.

The invention has many other features and objects which will be more fully described in connection with the accompanying drawing and 25 which .will be more particularly pointed out in and by the appended claims. 1

In the drawing:

Fig. 1 is a view in elevationof a piston having a. split skirt and showing the-device of my in- 30 vention applied thereto in dotted lines.

. Fig. 2 is a view of the piston looking from the left of Fig. 1.

Fig. 3 is a sectional view on line 3-4 of Fig. 1,

with the expander in elevation and partly in sec- 35 tion.

Fig. 4 is an inside view looking in the direction of the arrow in Fig. 3.

Fig. 5 is a view similar to Fig. 3, showing a it may be altered, after being installed, and

modified form of expander.

Fig. 6 is a view in side elevation of the expander shown in Fig. 5, detached from the piston. Fig. '7 is a perspective of the initial shape of the bar before the same has been bent to the desired form.

Like characters of reference designate partsthroughout the different figures of the drawing. I

- I have shown the device of my invention applied to a type .of piston in which the head is indicated at I, and is provided with the usual comiplement of ring grooves 2. 'Ihepiston is provided with a skirt 3 which is hung from the head lby an interior skeleton frame consisting of vertical members 4 and horizontal members 5. Bearings 6, for the crank pins, are shown formed integral with the vertical frame members 4. From Figs. 1 and 2, it will be seen that there is a. clearance between the bottom of head I and the top I of the skirt 3, and the latter is split or slit from the top I to the bottom 8, as indicated at 9.

It will be understood that my invention 'is not limited to this particular type of piston and is merely illustrated in .connection therewith to show how it may be applied thereto.

It is further understood that my invention is not limited as being applied to a skirt slit located in the particular position shown as it is merely essential that the skirt be divided in some way or in some location in order that the skirt may be expanded, and further, the extent to which it is divided is not material so long as the slit is suificient to permit of expansion of the skirt.

In the specific form shown, my improved expander is made froma bar of spring steel as shown in Fig. 7, and as indicated at H), and the same may, as shown, be flat so that it will occupy a single plane. It is first heated andshaped to a form, to be later described, while hot, and it is then allowed to.cool slowly in the air, or at any desired annealing low temperature so that it will not be tempered to the condition of resiliency that would be required from a spring havinga substantial responsive flexure. In the latter event the heated and shaped bar would of course be cooled in water or oil or by any sudden and well known means. Thus, after my expander has been shaped and given a sub-normal temper comparable to annealed steel, it will have a high degree of toughness and a low degree of resiliency, and these are the qualities which make the finished resilient article what I hereinafter term, self-sustaining in any shape to which and that the ends I! have been bent to abut against the inner face of the skirt, dependent upon the diameter thereof. Means is provided for anchoring the expander bar in place and, as shown, such means take the form of rivets I3, theheads l4 being disposed inside the skirt and the remaining ends I being counter-sunk either flush with the periphery of the skirt or slightly less than a flush relation therewith, which is a mechanical matter not important to'the invention. In fact, these rivets form an anchorage means which permits the bar to take its thrusts 'in the direction of its length, and any means such as sockets, for instance, which would perform this function, would be within the scope of the invention.

It will now be clear'that the expander bar It is disposed in substantially transverse relation to the length of the slit 9 and that the arch H .bridges said slit, and that the arch i's'formed so that it will be in spaced relation from the slit portion of the skirt. In other words, the central portion I l arches away from the feet or attaching terminals l2.

Next referring to the modified form shown in Figs. 5 and 6, it will be-seen that the arched feature is retained and for much the same purpose as in the preferred form except that there" is a series of arches,. the bar [6, from its initial flat form, as in Fig. 7, being corrugated, as indicated at ll. However, this modlfled'form is otherwise prepared in the same manner as the preferred form. The entire bar It is curved so that the radially outer corrugations or hills l8 abut against the inner face of the skirt while the radially in-.

ner hills I! project inside the skirt or toward the longitudinal axis thereof. I have shown the feet briefly recapitulated as follows:

It may be stated that the most important furction of this invention is to take up piston wear.

When the car is new, or when newpistons are fitted to re-bored cylinders, the pistons fit so tight that my expander is not called upon to function. However, just assoon as wear forms an objectionable clearance, then a few taps in the arch Il,tending to flatten the same, or a like treatment of any of the arches I1, will serve to lengthen the expander bars and thereby spread or expand the piston skirts. The expanding stress on the skirts will not be the same as would be exerted by a wholly rigid expander that might have threaded adjustment, for instance, but on the contrary, the expansive stress is of a yielding nature, and this is a vastly important quality.

Suppose for instance, that the arches were flattened to a too great extent and that after the engine got heated, the piston expansion added to the spread by the expander, caused the pistons to freeze in the cylinders, then, and in that event, my improved expanders would yield before such freezing action could take place, by reason of the fact that my 'expanders have a minute capacity to yield under all conditions and are never wholly rigid.

It tapping either 'form of arch,.the latter will of course be slightly deformed from its original shape in order to exercise an expanding thrust on the skirt, but of course such expansion will always be slight and hence the arch would never actually beentirely flattened against the wall of the skirt. Therefore it will be clear that even aftermaximum usage, and even after several successive expansions have been effected, there will always be an' arched central position spanning or bridging the slit in the skirt.

This is a very important feature of the invention since the arched form not only insures an effective spreading action, but it additionally insures a possible yielding action which would not be true if the arch in the preferred form, or all the arches of the modified form, were ever wholly flattened out. It will be clear that my improved bar expander would be just as unyielding and rigid as a straight flat bar if it were ever completely flattened.

Therefore itwill now be clear that by reason of the slow cooling of the shaped bar whereby it will have a low coemcient of resiliency, and the added fact that it always presents an arched form, I am able to achieve the dual function of a resilient or spring" expander that is self-sustaining in any shape changing or deformed contour to which it may be subjected.

It will thus be seen that the central portion H, or any one of the corrugations l1, may be flattened or altered in such a manner as to maintain tension of the bar in distending the piston skirt, in compensation for wear, or to increase the tension as the condition of the piston warrants.

It will be seen that my improved expansion bar is located far enough below the horizontal skeleton frame members 5, and at a suflicient elevation above the bottom 8 of the skirt 3, to make expansion of the skirt effective.

I desire to point out some of the fundamental distinctions between a leaf spring expanderand my improved bar expander.

A leaf spring is always relatively thin and is tempered to a relatively high degree of resiliency and is accordingly brittle. Therefore, sucha spring will instantly recoil to its original form when any attempt is made to deform or alter its shape unless the spring is re-tempered.

On the contrary, my expander is in the form of a spring steel bar, which differs fundamentally from a'leaf spring, by reason of the fact that this bar is of suflicient thickness or cross section to be self stable or self sustaining, as a result of its inherent stability, and irrespective of the fact that it is tempered. This bar is further distinguished from a, leaf spring expander by the fact that it is tempered to a low degree of resiliency and has a high degree of toughness. Hence, my bar can be tapped by a hammer, or wedged by a tool, to alter its original form and the bar will not only retain its altered form, but also, whatever resiliency was originally imparted to it during the tempering process.

While in Figs. 3 and 5, I have shown the ends 12 of bar II, and the ends IQ of bar It, riveted to the skirt, as a means of anchoring the bars thereto, still, it will be understood that in the broadest concept of the invention, the end l2 and l9, respectively, are disposed in distending relation to the piston skirt since the function of these bars is always to distend and not to contract the skirt, and hence I do not wish to be limited to the particular means shown of connecting or operatively locating the bars.

It is believed that the invention will be fully secured to the inner face of the piston skirton opposite sides .of the slit therein, the bar between the ends being of sinuous formation with the curves oi. the sinuous portion extending alternately inwardly away from the skirt and outward- 1y toward-the skirt.

2. As a piston expanding device For pistons having a split skirt, a bar formed of a single composition of metal having a single coeflicient of contraction and expansion and the ends 01' said ll bar being fixedly secured to the .inner face of the GEORGE c. max. 1o 

